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4 N. W. PRATT.

DEVICE FOR FASTENING HAND HOLE PLATES. No. 517,885. Patented r. 10,1894.

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SHINBTON. D. O.

v UNITED STATES PATENT ()FFICE.

N T. w. PRATT, or EEooKLYr NEw YORK.

DEVICE FOR FASTENING HAND-HOLE PLATES.

SPECIFICATION forming part of Letters Patent No. 517,885, dated April10,1894.

I Application filed March 3,1893- Serial No. 464,540- (No model.)

To all whom it may concern:

Be it known that I, N AT, W. PRATT, a citizen of the United States,residing at Brooklyn, in the county of Kings and State of New York, haveinvented certain new and useful Improvements in Devices forFasteningHand- Hole Plates, of which the following is a specification.

"This invention is particularly adapted for fastening hand hole platesupon the hand holes formed in the headers opposite the tubes in asectional water tube steam boiler; and the object of said invention isto secure the perfect seating of the hand. hole plate, and clampingplate, irrespective of variations in their positions, and in theperpendicularity of the bolt, which may arise from irregularities in theformation of the hand hole.

In order to accomplish the aforesaid ends, a bolt is herein providedwhich is ball-headed, being practically universally jointed to theclamping plate, and it. may also be universally jointed to the hand holeplate by employing a ball faced nut.

Referring to the accompanying drawings: Figure 1, is a side elevationpartly in section, showing the upper portion of a header of thedescription to which my invention applies; Fig. 2, a transverse sectionof Fig. 1, taken on the line 0ax,' Fig. 3, a sectional view showing amodified construction of the nut bearing surface; and Figs. 4, 5, 6 and7, a modified construction of the bolt, and the adaptation of the plateto an inclined header.

A, represents the tubular header composed of cast or wrought metal,contoured in serpentine form as shown in Fig. 2, having the hand holesB, formed therein at the extreme outward undulations of the serpentinecurves. The boiler tubes 0, as shown in Fig. 1, are inclined withreference to the vertical header A, expanded therein, and in order tomake the hand hole B, as small as possible so as to reduce the size ofthe hand hole plate or cap D, and so lessen the area under pressurewhich is held down by. the bolt E, the hand hole opening B, is made on arake, or inclined parallel with the tube 0. In Fig. 4:, the header isshown at right angles to the tubes and the 50 hand hole opening in aline with their axis.

The hand hole clamp F, composed of a malleable casting or drop forgingis of larger diameter than the circle of the hand hole, affordinglapping flanges a, and the two sides 0, d, are reduced so that the plateF, can be passed through the hand hole B, and then drawn outward againstit; the two ends e, f, forming a bearing against which the bolt E,pulls.

The solid hand hole clamp F, serves to keep the. hole B, practicallyclosed, if the bolt should give way. The hand hole plate F, is convexedinto the hole B, presenting beveled surfaces g, which serve to assist incentering the plate F, upon the margins of the opening B, when drawninto place. The .plate F, is

moreover webbed at h, on its concave side,

promoting strength.

The bolt E, is ball headed at 1 fitting the hemispherical socket j, inplate F, and the shank of the bolt plays loosely in the hole throughwhich it is passed. In this instance the shank of the bolt is squared atk, preventing it from turning when the nut G is screwed up.

When the face of the hand hole plate D, is seated upon the aperture ofthe header A, and the nut G drawn against it, the ball head of the boltbears on the inside of the clamp F,

, allowing the clamp to rest equally on all sides of the hand holeopening, and yet get a square pull at the bolt, so that the faces of thehand hole plate and nut where they come in contact, are not thrown outof line by any stifiness of the bolt.

It occurs in practice, especially in wrought iron headers, and sometimesin those ofcast iron, that the thickness of the casting or forging at m,or 'n, representing the depth of the margins of the hand hole, isunequal, in which case, if a stiff bolt rigidly projected from the clampF, or having a square shouldered head seating thereon, is used, there isa tendency to throw the strain more on one side than another, and tothrow the fitted faces of the nuts and plates out of line with eachother. Moreover, when the plates F, D, are being clamped together,whether they lie parallel or not, the ball headed bolt E, willaccommodate itself to the lateral adjustment of the nut G, such asrequired in order to find its seat and abut equally on all sides of thebolt.

It will be observed that the threads 0, of the bolt E, project beyondthe diameter of the neck 19, rendering the full strength of the boltunimpaired by reduction of the cross sectional area of the material orstock of which it is composed, thus providing against fracture assometimes occurs when the threads are cut within the normal diameter ofthe bolt.

The modification in Fig. 3, consists in pro- Viding the seating surfaceof the nut G, upon the hand hole plate D, with a convexity whereby theseat forms a part of an imaginary sphere indicated by the dotted line q,thereby constituting a practically ball headed nut. Thus two points ofuniversal play are allowed in the bolt E, further promoting perfectseating of the parts to be clamped.

The modifications shown in Figs. 4, 5, 6 and 7, consist in dispensingwith the square portion of the body or shank of the bolt, and making thehead of the bolt square as shown at K, the socket in the clamp F beingof corresponding shape but slightly larger in order to give sufficientclearance to allow the bolt to rock on its ball bearing and yet preventit from turning when the nut is applied.

What I claim, and desire to secure by Letters Patent, is

1. A steam generator having a header and inclined tubes, hand holeopenings in said header in axial line with the tubes, and a cover plateand clamp secured with the universally jointed bolt as set forth.

2. A steam generator having a vertical header and inclined connectedtubes, the hand hole openings in said header being formed in axial linewith the inclined tubes and fitted with a cover plate and clampconnected by a bolt arranged at right angles to the face of the headerand universally jointed to the clamp, substantially as and for thepurpose set forth.

3. A clamp or yoke for cover plates of steam boilers of greater diameterthan the opening, having two of its parallel sides reduced combined witha securing bolt having a ball bearing head upon which the yoke is freeto oscillate when adjusted to place, and a squared portion whichprevents it from turning when in place, as set forth.

4. A clamp bolt for securing a cover plate constructed with a ballbearing head and ashauk or body of less diameter through the plateaperture whereby the bearing faces of the nut and plate are brought inuniform contact, and any lateral strain on the threaded portion of thebolt relieved as set forth.

NAT. W. PRATT.

Witnesses:

CHAS. W. FORBES, E. M AC ENTEE.

